The Supreme Court's revamped conservative majority flexed its muscle Monday in three 5-4 decisions that undercut precedents set by more liberal courts.

The rulings - which included decisions that weaken restrictions on broadcast ads during election campaigns and that narrow students' speech rights in schools - reflected how President Bush's appointees, Chief Justice John Roberts and Justice Samuel Alito, have begun to move the court toward the right. But Monday's decisions also suggest that Roberts and Alito are reluctant to completely gut court precedents, a tactic favored by conservative Justices Antonin Scalia and Clarence Thomas.

The less audacious approach shown by Roberts and Alito seemed to matter little to the court's increasingly frustrated liberal wing - John Paul Stevens, David Souter, Ruth Bader Ginsburg and Stephen Breyer - who on Monday issued fierce dissents protesting the court's new direction.

"The court (and, I think, the country) loses when important precedent is overruled without good reason," Souter wrote in objecting to the campaign finance ruling.

In Monday's most significant ruling, the court carved into the landmark McCain-Feingold campaign finance law by opening the door to corporate and union financing of broadcast ads just before an election. The decision is likely to lead to an advertising bonanza by such groups before the 2008 elections.